From bad8adda4142ff5ba522511c03756324b83fb124 Mon Sep 17 00:00:00 2001 From: M A Ramdhan Date: Wed, 5 Jul 2023 12:15:30 -0400 Subject: [PATCH] UPSTREAM: net/sched: cls_fw: Fix improper refcount update leads to use-after-free [ Upstream commit 0323bce598eea038714f941ce2b22541c46d488f ] In the event of a failure in tcf_change_indev(), fw_set_parms() will immediately return an error after incrementing or decrementing reference counter in tcf_bind_filter(). If attacker can control reference counter to zero and make reference freed, leading to use after free. In order to prevent this, move the point of possible failure above the point where the TC_FW_CLASSID is handled. Bug: 292252062 Bug: 290783303 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: M A Ramdhan Signed-off-by: M A Ramdhan Acked-by: Jamal Hadi Salim Reviewed-by: Pedro Tammela Message-ID: <20230705161530.52003-1-ramdhan@starlabs.sg> Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin (cherry picked from commit c91fb29bb07ee4dd40aabd1e41f19c0f92ac3199) Signed-off-by: Lee Jones Change-Id: I9bf6f540b4eb23ea5641fb3efe6f3e621d7b6151 --- net/sched/cls_fw.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c index ec945294626a..41f0898a5a56 100644 --- a/net/sched/cls_fw.c +++ b/net/sched/cls_fw.c @@ -210,11 +210,6 @@ static int fw_set_parms(struct net *net, struct tcf_proto *tp, if (err < 0) return err; - if (tb[TCA_FW_CLASSID]) { - f->res.classid = nla_get_u32(tb[TCA_FW_CLASSID]); - tcf_bind_filter(tp, &f->res, base); - } - if (tb[TCA_FW_INDEV]) { int ret; ret = tcf_change_indev(net, tb[TCA_FW_INDEV], extack); @@ -231,6 +226,11 @@ static int fw_set_parms(struct net *net, struct tcf_proto *tp, } else if (head->mask != 0xFFFFFFFF) return err; + if (tb[TCA_FW_CLASSID]) { + f->res.classid = nla_get_u32(tb[TCA_FW_CLASSID]); + tcf_bind_filter(tp, &f->res, base); + } + return 0; }